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Building Software Packages for Linux Mendel Leo Cooper <mailto:thegrendel@theriver.com> http://personal.riverusers.com/~thegrendel/ v1.52, 27 December 1997 This is a comprehensive guide to building "generic" UNIX software dis¡ tributions under Linux. 1. Introduction Many software packages for the various flavors of UNIX, including Linux, are distributed as compressed archives of source files. The same package may be "built" to run on different target machines, and this saves the author of the software from having to produce multiple distributions. A single distribution of a software package may thus end up running, in various incarnations, on an Intel box, a DEC Alpha, a RISC workstation, or even a mainframe. Unfortunately, this puts the responsibility of actually "building" the software on the end user, the de facto "system administrator", the fellow sitting at the keyboard... you. Take heart, though, the process is not nearly as terrifying or mysterious as it seems, as this guide will demonstrate. 2. Getting Started You have downloaded or otherwise acquired a software package. Most likely it is archived (tarred) and compressed (gzipped), in .tar.gz or .tgz form. First copy it to a working directory. Then untar and gunzip it. The appropriate command for this is tar xzvf filename, where filename is the name of the software file, of course. The de- archiving process will usually install the appropriate files in subdirectories it will create. Note that if the package name has a .Z suffix, it will require uncompress PACKAGENAME, then tar xvf PACKAGENAME rather than the above procedure. Sometimes the archived file must be untarred and installed from the user's home directory, or perhaps in a certain other directory, as specified in the package's config info. Should you get an error message attempting to untar it, this may be the reason. Read the package docs, especially the README and/or Install files, if present, and edit the config files and/or Makefiles as necessary, consistent with the installation instructions. Note that you would not ordinarily alter the Imake file, since this could have unforseen consequences. Some software packages permit automating this process by running make install to emplace the binaries in the appropriate system areas. Occasionally, you may need to update or incorporate bug fixes into the unarchived source files using a patch file that lists the changes. The doc files and/or README file will inform you should this be the case. The normal syntax for invoking Larry Wall's powerful patch utility is patch < patchfile. You may now proceed to the build stage of the process. 3. Using Make The Makefile is the key to the build process. In its simplest form, a Makefile is a script for compiling or building the "binaries", the executable portions of a package. The Makefile can also provide a means of updating a software package without having to recompile every single source file in it, but that is a different story (or a different article). At some point, the Makefile launches cc or gcc. This is actually a preprocessor, a C (or C++) compiler, and a linker, invoked in that order. This process converts the source into the binaries, the actual executables. Invoking make usually involves just typing make. This generally builds all the necessary executable files for the package in question. However, make can also do other tasks, such as installing the files in their proper directories (make install)and removing stale object files (make clean). Running make -n permits previewing the build process, as it prints out all the commands that would be triggered by a make, without actually executing them. Only the simplest software uses a generic Makefile. More complex installations require tailoring the Makefile according to the location of libraries, include files, and resources on your particular machine. This is especially the case when the build needs the X11 libraries to install. Imake and xmkmf accomplish this task. An Imakefile is, to quote the man page, a "template" Makefile. The imake utility constructs a Makefile appropriate for your system from the Imakefile. In almost all cases, however, you would run xmkmf, a shell script that invokes imake, a front end for it. Check the README or INSTALL file included in the software archive for specific instructions. Read the imake and xmkmf man pages for a more detailed analysis of the procedure.. Be aware that xmkmf and make may need to be invoked as root, especially when doing a make install to move the binaries over to the /usr/bin or /usr/local/bin directories. Using make as an ordinary user without root privileges will likely result in write access denied error messages because you lack write permission to system directories. Check also that the binaries created have the proper execute permissions for you and any other appropriate users. Invoking xmkmf uses the Imake file to build a new Makefile appropriate for your system. You would normally invoke xmkmf with the -a argument, to automatically do a make Makefiles, make includes, and make depend. This sets the variables and defines the library locations for the compiler and linker. Sometimes, there will be no Imake file, instead there will be an INSTALL or configure script that will accomplish this purpose. Note that if you run configure, it should be invoked as ./configure to ensure that the correct configure script in the current directory is called. In most cases, the README file included with the distribution will explain the install procedure. It is usually a good idea to visually inspect the Makefile that xmkmf or one of the install scripts builds. The Makefile will normally be correct for your system, but you may occasionally be required to "tweak" it or correct errors manually. Your general installation procedure will therefore be: ╖ Read the README file and other applicable docs. ╖ Run xmkmf -a, or the INSTALL or configure script. ╖ Check the Makefile. ╖ If necessary, run make clean, make Makefiles, make includes, and make depend. ╖ Run make. ╖ Check file permissions. ╖ If necessary, run make install. 4. Troubleshooting If xmkmf and/or make succeeded without errors, you may proceed to the ``next section''. However, in "real life", few things work right the first time. This is when your resourcefulness is put to the test. 4.1. Link Errors ╖ Suppose make fails with a Link error: -lX11: No such file or directory, even after xmkmf has been invoked. This may mean that the Imake file was not set up properly. Check the first part of the Makefile for lines such as: LIB= -L/usr/X11/lib INCLUDE= -I/usr/X11/include/X11 LIBS= -lX11 -lc -lm The -L and -I switches tell the compiler and linker where to look for the library and include files, respectively. In this example, the X11 libraries should be in the /usr/X11/lib directory, and the X11 include files should be in the /usr/X11/include/X11 directory. If this is incorrect for your machine, make the necessary changes to the Makefile and try the make again. ╖ In a very few cases, running ldconfig as root may be the solution: # /etc/ldconfig -n /lib will update the shared library symbolic links. This should not be necessary under normal circumstances. ╖ Yet another thing to try if xmkmf fails is the following script: make -DUseInstalled -I/usr/X386/lib/X11/config ╖ Sometimes the source needs the older release X11R5 libraries to build. If you have the R5 libs in /usr/X11R6/lib (you were given the option of having them when first installing Linux), then you need only ensure that you have the links that the software needs to build. The R5 libs are named libX11.so.3.1.0, libXaw.so.3.1.0, and libXt.so.3.1.0. You generally need links, such as libX11.so.3 -> libX11.so.3.1.0. Possibly the software will also need a link of the form libX11.so -> libX11.so.3.1.0. Of course, to create a "missing" link, use the command ln -s libX11.so.3.1.0 libX11.so, as root. ╖ Some packages will require you to install updated versions of one or more libraries. For example, the StarOffice suite from StarDivision GmbH is notorious for needing a libc version 5.4.4 or greater. As root, you would need to copy one or more libraries to the appropriate directories, remove the old libraries, then reset the symbolic links. Caution: Exercise extreme care in this, as you can render your system nonfunctional if you screw up. You can usually find updated libraries at Sunsite <ftp://sunsite.unc.edu>. 4.2. Other Problems ╖ An installed Perl or shell script gives you a No such file or directory error message. In this case, check the file permissions to make sure the file is executable and check the file header to ascertain whether the shell or program invoked by the script is in the place specified. For example, the scrip may begin with: #!/usr/local/bin/perl If Perl is in fact installed in your /usr/bin directory instead of the /usr/local/bin one, then the script will not run. There are two meth¡ ods of correcting this. The script file header may be changed to #!/usr/bin/perl, or a symbolic link to the correct directory may be added, ln -s /usr/bin/perl /usr/local/bin/perl. ╖ Some X11 software requires the Motif libraries to build. The standard Linux distributions do not have the Motif libraries installed, and at present Motif costs an extra $100-$200 (though the freeware Lesstif <http://www.lesstif.org/> also works in many cases). If you need Motif to build a certain package, but lack the Motif libraries, it may be possible to obtain statically linked binaries. Static linking incorporates the library routines in the binaries themselves. This results in much larger binary files, but the code will run on systems lacking the libraries. ╖ Running a configure script creates a strange Makefile, one seemingly unrelated to the package you are attempting to build. This means the wrong configure ran, one found somewhere else in your path. Always invoke configure as ./configure to prevent this. ╖ Some programs require having setuid root, in order to run with root privileges. The command to implement this is chmod u+s filename, as root (note that the program must already be owned by root). This has the effect of setting the setuid bit in the file permissions. This issue comes up when the program accesses the system hardware, such as a modem or CD ROM drive, or when the SVGA libs are invoked from console mode, as in one particularly notorious emulation package. If a program works when run by root, but gives access denied error messages to an ordinary user, suspect this as the cause. Warning: A program with setuid as root may pose a security risk to your system. The program runs with root privileges and thus has the potential for doing significant damage. Make certain that you know what the program does, by looking at the source if necessary, before setting the setuid bit. 4.3. Tweaking and fine tuning You may wish to examine the Makefile to make certain that the best compilation options for your system are invoked. For example, setting the -O2 flag chooses the highest level of optimization and the -fomit- frame-pointer flag results in a smaller binary (though debugging will then be disabled). Do not play around with this unless you know what you are doing, and in any case, until after a trial build works. 4.4. Where to go for more help In my experience, perhaps 25% of applications build "right out of the box". Another 50% or so can be "persuaded" to build with an effort ranging from trivial to herculean. That still means a significant number of packages will not build no matter what. Even then, the Intel ELF and/or a.out binaries for these might possibly be found at Sunsite <ftp://sunsite.unc.edu>, the TSX-11 archive <ftp://tsx-11.mit.edu> or other places. Perhaps the author of the software can supply the binaries compiled for your particular flavor of machine. Note that if you obtain precompiled binaries, you will need to check for compatibility with your system: ╖ The binaries must run on your hardware (i.e., Intel x86). ╖ The binaries must be compatible with your kernel (i.e., a.out or ELF). ╖ Your libraries must be up to date. If all else fails, you may find help in the appropriate newsgroups, such as comp.os.linux.x or comp.os.linux.development. Once in a while, though, you are just plain out of luck, but hey, it was fun trying. 5. Final Steps Read the software package documentation to determine whether certain environmental variables need setting (in .bashrc or .cshrc) and if the .Xdefaults and .Xresources files need customizing. There may be an applications default file, usually named Xfoo.ad in the original Xfoo distribution. If so, edit the Xfoo.ad file to customize it for your machine, then rename (mv) it Xfoo and install it in the /usr/lib/X11/app-defaults directory, as root. Failure to do this may cause the software to behave strangely or even refuse to run. Most software packages come with one or more preformatted man pages. As root, copy the Xfoo.man file to the appropriate /usr/man directory (man1 - man9), and rename it accordingly. For example, if Xfoo.man ends up in /usr/man/man4, it should be renamed Xfoo.4 (mv Xfoo.man Xfoo.4). By convention, user commands go in man1, games in man6, and administration packages in man8 (see the man docs for more details). Of course, you may deviate from this on your own system, if you like. Some packages will not install the binaries in the appropriate system directories, that is, they are missing the install option in the Makefile. Should this be the case, you can install the binaries manually by copying the binaries to the usr/local/bin directory, as root. Note that some or all of the above procedures should, in most cases, be handled automatically by a make install. If so, the README or INSTALL doc file will specify this. 6. First Example: Xscrabble Matt Chapman's Xscrabble seemed like a program that would be interesting to have, since I happen to be an avid Scrabble[TM] player. I downloaded it, uncompressed it, and built it following the procedure in the README file: xmkmf make Makefiles make includes make Of course it did not work... ______________________________________________________________________ gcc -o xscrab -O2 -O -L/usr/X11R6/lib init.o xinit.o misc.o moves.o cmove.o main.o xutils.o mess.o popup.o widgets.o display.o user.o CircPerc.o -lXaw -lXmu -lXExExt -lXext -lX11 -lXt -lSM -lICE -lXExExt -lXext -lX11 -lXpm -L../Xc -lXc BarGraf.o(.text+0xe7): undefined reference to `XtAddConverter' BarGraf.o(.text+0x29a): undefined reference to `XSetClipMask' BarGraf.o(.text+0x2ff): undefined reference to `XSetClipRectangles' BarGraf.o(.text+0x375): undefined reference to `XDrawString' BarGraf.o(.text+0x3e7): undefined reference to `XDrawLine' etc. etc. etc... ______________________________________________________________________ I enquired about this in the comp.os.linux.x newsgroup, and someone kindly pointed out that apparently the Xt, Xaw, Xmu, and X11 libs were not being found at the link stage. Hmmm... There were two main Makefiles, and the one in the src directory caught my interest. One line in the Makefile defined LOCAL_LIBS as: LOCAL_LIBS = $(XAWLIB) $(XMULIB) $(XTOOLLIB) $(XLIB) Here were references to the libs not being found by the linker. Looking for the next reference to LOCAL_LIBS, I saw on line 495 of that Makefile: $(CCLINK) -o $@ $(LDOPTIONS) $(OBJS) $(LOCAL_LIBS) $(LDLIBS) $(EXTRA_LOAD_FLAGS) Now what were these LDLIBS? LDLIBS = $(LDPOSTLIB) $(THREADS_LIBS) $(SYS_LIBRARIES) $(EXTRA_LIBRARIES) The SYS_LIBRARIES were: SYS_LIBRARIES = -lXpm -L../Xc -lXc Yes! Here were the missing libraries. Possibly the linker needed to see the LDLIBS before the LOCAL_LIBS... So, the first thing to try was to modify the Makefile by transposing the $(LOCAL_LIBS) and $(LDLIBS) on line 495, so it would now read: $(CCLINK) -o $@ $(LDOPTIONS) $(OBJS) $(LDLIBS) $(LOCAL_LIBS) $(EXTRA_LOAD_FLAGS) ^^^^^^^^^^^^^^^^^^^^^^^ I tried running make again with the above change, and lo and behold, it worked this time. Of course, Xscrabble still needed some fine tuning and twiddling, such as renaming the dictionary and commenting out some assert statements in one of the source files, but since then it has provided me with many hours of pleasure. You may e-mail Matt Chapman <mailto:matt@belgarath.demon.co.uk>, and download Xscrabble from his home page <http://www.belgarath.demon.co.uk/programs/index.html>. ______________________________________________________________________ Scrabble is a registered trademark of the Milton Bradley Co., Inc. ______________________________________________________________________ 7. Second Example: Xloadimage This example poses an easier problem. The xloadimage program seemed a useful addition to my set of graphic tools. I copied the xloadi41.gz file directly from the source directory on the CD included with the excellent ``X User Tools'' book, by Mui and Quercia. As expected, tar xzvf unarchives the files. The make, however, produces a nasty- looking error and terminates. ______________________________________________________________________ gcc -c -O -fstrength-reduce -finline-functions -fforce-mem -fforce-addr -DSYSV -I/usr/X11R6/include -DSYSPATHFILE=\"/usr/lib/X11/Xloadimage\" mcidas.c In file included from /usr/include/stdlib.h:32, from image.h:23, from xloadimage.h:15, from mcidas.c:7: /usr/lib/gcc-lib/i486-linux/2.6.3/include/stddef.h:215: conflicting types for `wchar_t' /usr/X11R6/include/X11/Xlib.h:74: previous declaration of `wchar_t' make[1]: *** [mcidas.o] Error 1 make[1]: Leaving directory `/home/thegrendel/tst/xloadimage.4.1' make: *** [default] Error 2 ______________________________________________________________________ The error message contains the essential clue. Looking at the file image.h, line 23... ______________________________________________________________________ #include <stdlib.h> ______________________________________________________________________ Aha, somewhere in the source for xloadimage, wchar_t has been rede¡ fined from what was specified in the standard include file, stdlib.h. Let us first try commenting out line 23 in image.h, as perhaps the stdlib.h include is not, after all, necessary. At this point, the build proceeds without any fatal errors. The xloadimage program functions correctly now. 8. Third Example: Fortune This final example requires some knowledge of C programming. The majority of Linux software is written in C, and learning at least a little bit of C would certainly be an asset for anyone serious about software installation. The notorious fortune program displays up a humorous saying, a "fortune cookie", every time Linux boots up. Unfortunately (pun intended), attempting to build fortune on a Red Hat distribution with a 2.0.30 kernel generates fatal errors. ______________________________________________________________________ ~/fortune# make all gcc -O2 -Wall -fomit-frame-pointer -pipe -c fortune.c -o fortune.o fortune.c: In function `add_dir': fortune.c:551: structure has no member named `d_namlen' fortune.c:553: structure has no member named `d_namlen' make[1]: *** [fortune.o] Error 1 make[1]: Leaving directory `/home/thegrendel/for/fortune/fortune' make: *** [fortune-bin] Error 2 ______________________________________________________________________ Looking at fortune.c, the pertinent lines are these. ______________________________________________________________________ if (dirent->d_namlen == 0) continue; name = copy(dirent->d_name, dirent->d_namlen); ______________________________________________________________________ We need to find the structure dirent, but it is not declared in the fortune.c file, nor does a grep dirent show it in any of the other source files. However, at the top of fortune.c, there is the following line. ______________________________________________________________________ #include <dirent.h> ______________________________________________________________________ This appears to be a system library include file, therefore, the logical place to look for dirent.h is in /usr/include. Indeed, there does exist a dirent.h file in /usr/include, but that file does not contain the declaration of the dirent structure. There is, however, a reference to another dirent.h file. ______________________________________________________________________ #include <linux/dirent.h> ______________________________________________________________________ At last, going to /usr/include/linux/dirent.h, we find the structure declaration we need. ______________________________________________________________________ struct dirent { long d_ino; __kernel_off_t d_off; unsigned short d_reclen; char d_name[256]; /* We must not include limits.h! */ }; ______________________________________________________________________ Sure enough, the structure declaration contains no d_namelen, but there are a couple of "candidates" for its equivalent. The most likely of these is d_reclen, since this structure member probably represents the length of something and it is a short integer. The other possibility, d_ino, could be an inode number, judging by its name and type. As a matter of fact, we are probably dealing with a "directory entry" structure, and these elements represent attributes of a file, its name, inode, and length (in blocks). This would seem to validate our guess. Let us edit the file fortune.c, and change the two d_namelen references in lines 551 and 553 to d_reclen. Try a make all again. Success. It builds without errors. We can now get our "cheap thrills" from fortune. 9. Where to Find Source Archives Now that you are eager to use your newly acquired knowledge to add utilities and other goodies to your system, you may find them online at the Linux Applications and Utilities Page <http://www.redhat.com/linux-info/linux-app-list/linapps.html>, or on one of the very reasonably priced CD ROM archives by Red Hat <http://www.redhat.com/>, InfoMagic <mailto:orders@infomagic.com>, and others. A comprehensive repository of source code is the comp sources UNIX archive <ftp://ftp.vix.com/pub/usenet/comp.sources.unix/>. Much UNIX source code is posted on the alt.sources newsgroup. If you are looking for particular source code packages, you may post on the related alt.sources.wanted newsgroup. Another good place to check is the comp.os.linux.announce newsgroup. To get on the Unix sources <mailto:unix-sources@pa.dec.com> mailing list, send a subscribe message there. Archives for the alt.sources newsgroup are at the following ftp sites: ╖ ftp.sterling.com/usenet/alt.sources/ <ftp://ftp.sterling.com/usenet/alt.sources/> ╖ wuarchive.wustl.edu/usenet/alt.sources/articles <ftp://wuarchive.wustl.edu/usenet/alt.sources/articles> ╖ src.doc.ic.ac.uk/usenet/alt.sources/articles <ftp://src.doc.ic.ac.uk/usenet/alt.sources/articles> 10. Final Words To sum up, persistence makes all the difference (and a high frustration threshold certainly helps). As in all endeavors, learning from mistakes is critically important. Each misstep, every failure contributes to the body of knowledge that will lead to mastery of the art of building software. 11. References and Further Reading BORLAND C++ TOOLS AND UTILITIES GUIDE, Borland International, 1992, pp. 9-42. [One of the manuals distributed with Borland C++, ver. 3.1. Gives a fairly good intro to make syntax and concepts, using Borland's crippled implementation for DOS.] DuBois, Paul: SOFTWARE PORTABILITY WITH IMAKE, O'Reilly and Associates, 1996, ISBN 1-56592-226-3. [This is reputed to be the definitive imake reference, though I did not have it available when writing this article.] Frisch, Aeleen: ESSENTIAL SYSTEM ADMINISTRATION, O'Reilly and Associates, 1995, ISBN 1-56592-127-5. [This otherwise excellent sys admin handbook has only sketchy coverage of software building.] Lehey, Greg: PORTING UNIX SOFTWARE, O'Reilly and Associates, 1995, ISBN 1-56592-126-7. Mui, Linda and Valerie Quercia: X USER TOOLS, O'Reilly and Associates, 1994, ISBN 1-56592-019-8, pp. 734-760. Oram, Andrew and Steve Talbott: MANAGING PROJECTS WITH MAKE, O'Reilly and Associates, 1991, ISBN 0-937175-90-0. Peek, Jerry and Tim O'Reilly and Mike Loukides: UNIX POWER TOOLS, O'Reilly and Associates / Random House, 1997, ISBN 1-56592-260-3. [A wonderful source of ideas, and tons of utilities you may end up building from the source code, using the methods discussed in this article.] Stallman, Richard M. and Roland McGrath: GNU MAKE, Free Software Foundation, 1995, ISBN 1-882114-78-7. [Should be required reading.] Welsh, Matt and Lar Kaufman: RUNNING LINUX, O'Reilly and Associates, 1996, ISBN 1-56592-151-8. [Still the best overall Linux reference, though lacking in depth in some areas.] And, of course, the man pages for make, imake, xmkmf, gcc, ldconfig, gzip, tar, and patch.